Cutting tool



Dec. 9, 1969 H. M. BRIZZOLARA CUTTING TOOL Filed Jan. 22, 1968 INVENTOR Hemy M. Brlzzoium ATTORNEY United States Patent 3,482,484 CUTTING TOOL Henry M. Brizzolara, Allentown, Pa., assignor to Atlas Chemical Industries, Inc., Wilmington, Del., a corporation of Delaware Filed Jan. 22, 1968, Ser. No. 699,454 Int. Cl. F41f 1/00 US. Cl. 891 Claims ABSTRACT OF THE DISCLOSURE A cutter tool is disclosed having explosive charge sealing means for containing a charge and for preventing desensitization thereof by water even under high pressure conditions. The explosive charge sealing means includes a water-sealing rupturable disc disposed over a back-up plate capable of supporting high pressures in a direction against the explosive charge while providing little resistance against the force generated upon detonation of the explosive charge.

This invention relates to an explosively actuated cutting tool and more particularly to such a cutting tool having an explosive charge sealing means for containing an explosive charge and for preventing desensitization thereof by water even under high pressure environmental conditions.

Explosively actuated cutting devices are known to the art for use in severing cables, reefing lines and the like. These various devices, however, are insufficient for protecting against water damage of the explosive charge and, in particular, are inefficientwhen the device is to be used under extremely high water pressures such as to about 10,000 p.s.i. or more.

One difiiculty in preparing an explosively actuated cutting device for use underhigh water pressure conditions is that water excluding means must be sufiiciently strong to withstand the water pressure but must also be readily ruptured by the explosive force of the detonated charge in order to be useful. Otherwise, the force of the explosion will destroy the device rather than be channeled into a useful direction.

The present invention generally provides an explosively actuated cutting tool having an explosive charge sealing means for containing an explosive charge and for preventing desensitization thereof by water even under high pressure environmental conditions. The explosive charge sealing means includes a relatively thin, water-sealing rupturable disc disposed over a back-up plate capable of supporting high pressures in a direction against the explosive charge while providing little resistance against the force generated upon detonation of the explosive charge.

The present invention will become more apparent from the following detailed description taken with regard to the accompanying drawing in which like numerals represent the same elements throughout the several views.

In the drawing:

FIG. 1 is a half-section elevational view of the cutting tool of the present invention;

FIG. 2 is an end view thereof;

FIG. 3 is a half-section side elevational view of the cutting tool of FIG. 1; and

FIG. 4 is an enlarged portion of the explosive charge sealing means used in the cutting tool of this invention.

Referring to FIGS. 1-4, there is illustrated cutting tool formed of any suitable material including for example, stainless steel, and having tubular casing 12 as the outer housing with U-shaped slot 14 at one end thereof. Removable anvil plate 16 may be held by screws 18 or the like, to housing 20 which is formed as part of the tubular casing.

Opposite U-shaped slot 14 along the tubular casing is internally threaded end 22 for receiving tubular explosive fitting 24 which serves as a convenient means to contain explosive charge 26. Any explosive material may be employed for explosive charge 26 which, upon initiation, provides a force sufiicient to operate the present cutting tool and which is generally water duddable. Back-up plate 28 is illustrated seated on shoulder 30 formed around the internal surface of the tubular explosive fitting and serves, because it is so close-fitting, to contain the explosive charge while preventing deformation of rupturable sealing disc 32 when exposed to high external pressures. Other means may also be used to support back-up plate 28 instead of shoulder 30, such as pins or the like as desired.

As illustrated in the enlarged view of FIG. 4, a suitable welding 34, or other adhesive means, preferably capable of providing a waterproofing seal, may be employed about the periphery of rupturable sealing disc 32 to present a water tight seal about disc 32 to tubular explosive fitting 24. In effect, therefore, the sealing means for the tubular explosive fitting includes a readily removable, close-fitting, pressure retaining member 28 and a covering, water-sealing readily rupturable disc 32 or related waterproofing means thereon, in the removable direction. The readily removable pressure-retaining member 28 is forced through rupturable disc 32 upon initiation of the explosive charge and the gases generated are then channeled into a useful direction.

Screw type electrode plug 36 is provided and screw threaded for waterproof union into the open end of tubular explosive fitting 24 such that electrodes 38 project through opening 40 into or otherwise positioned relative to explosive charge 26 for detonation. Electrodes 38 having a high resistance bridge wire 39 therebetween are supported by tubular insulation 42 within electrode plug 36. Ignition composition 41 may be disposed as a bead of material about high electric resistance bridge wire 39 for use in initiating explosive charge 26. Ignition composition 41 may include materials such as, for example, cuprous acetylide, diazodinitrophenol, lead mononitroresorcinate, mixtures of lead mononitroresorcinate and potassium chlorate, or related materials and mixtures thereof. Threads 44 may be usefully included on electrode plug 36 for attachment through a communication means to a suitable firing device, not shown, which causes, upon command, bridge wire 39 to ignite composition 41 which, in turn, initiates the explosive charge. Other attachments means on electrode plug 36 in place of threads 44 may also be employed.

Shearing element illustrated as piston 46 is formed with straight knife edge cutting blade 48 although other blade configurations may be also suitably employed. The length of the straight knife edge cutting blade may be approximately that of the inner diameter of casing 12 and is desirably formed of a hard, sharpened material so that it will effectively sever a line or cable disposed within U-shaped slot 14. Piston 46 is held by shear pin 50 or related temporary piston holding means such as a wedge member to assure proper rotational position relative to the line to be severed when piston 46 is in retracted position. During the cutting stroke of the piston, shear pin 50 is broken as the piston is projected by the actuated assembly 52 and gas sealing member 54.

Shear pin 50 is designed to fail after a force is applied on piston 46 which force is generally at least suflicient to sever a line disposed in U-shaped slot 14. Thus, the gas generated by the explosive charge causes shear pin 50 to fail after a predetermined pressure has been built up and with ample energy to almost instantaneously accelerate blade 48 to a high velocity for the cutting step.

Due to the relative short stroke required by the piston to complete the cutting operation coupled with the high acceleration rate thereof, once released by shear pin 50, there is little or no opportunity for the blade to rotate from the initial retracted position. If desired, piston 46 may be keyed to casing 12 such as by a tongue and groove arrangement to prevent rotational movement of the knife blade during the cutting stroke. However, such a keyed arrangement tends to increase the frictional drag of the piston and is generally not necessary.

Gas seal 52 is disposed within casing 12 intermediate explosive assembly 24 and seal 54 adjacent piston 46. The gas seal may be placed around the periphery of inner surface of the casing 12 to insure an effective gas seal and efficient propelling of piston 46 by the generated gases from the actuated explosive assembly, Both gas seal 52 and seal 54 may be formed of any suitable material conventionally used in the art, as desired.

Piston 46 may be provided with channel 56 for optionally containing O-ring 58. O-ring 58 may thus provide an additional gas sealing factor while permitting piston 46 to conveniently move with little resistance in casing 12 upon initiation of explosive charge 26.

Although the cutting tool of the present invention is primarily intended for use in connection with cutting cables at water levels where pressures are above about 10,000 p.s.i., it is obvious that the present tool may be useful where it is desired to remotely sever a line element in a dependable and efiicient manner. The present cutting tool may perform under wet environmental conditions which would otherwise affect the operation of explosively actuated cutting tools by dudding the explosive charge through exposure to such environmental conditions over extended periods of time.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from this invention.

What is claimed is:

1. In an underwater cutting tool having:

(a) a casing having provision for the insertion of a line therethrough,

(b) a linearly movable shearing element disposed within said casing positioned to one side of said provision,

(c) an anvil fixed to said casing and positioned in line with said shearing element at the other side of said provision, and

(d) an electrically activated explosive charge containing device positioned so that when said charge explodes the force of said explosive is directed against said shearing element driving it across said provision and into said anvil,

an improved explosive charge sealing means for said electrically activated explosive charge containing device, said means comprising:

(a) a support means,

(b) a readily removable back-up plate which rests on said support means, said back-up plate being capable of withstanding pressures of about 10,000 p.s.i., and

(c) a disc rupturable by said explosion, said disc being positioned over said back-up plate and being welded to said support means.

2. The underwater cutting tool of claim 1 wherein said shearing element is :a piston having a knife blade projecting therefrom.

3. The underwater cutting tool of claim 1 wherein said shearing element prior to said explosion is held in place by means of a shear pin.

4, The underwater cutting tool of claim 1 wherein said provision is adjacent said anvil and said anvil is removable so that a line may be placed in said provision.

5. The underwater cutting tool of claim 1 wherein said support means is a shoulder.

References Cited UNITED STATES PATENTS 2,806,442 9/1957 Temple 89-1 X 2,918,003 12/1959 Temple 10239 X 3,277,255 10/1966 Mattsson et a1. 89-1 X SAMUEL W. ENGLE, Primary Examiner U.S. Cl. X.R. 

